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30
Interference modeling of cognitive radio networks
 in Proc. IEEE VTC’08Spring
, 2008
"... Abstract—In this paper, we present an interference model for cognitive radio (CR) networks employing power control or contention control scheme. The probability density functions (PDFs) of the interference received at a primary receiver from a CR network are derived for two cases. For the first case ..."
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Abstract—In this paper, we present an interference model for cognitive radio (CR) networks employing power control or contention control scheme. The probability density functions (PDFs) of the interference received at a primary receiver from a CR network are derived for two cases. For the first case, a power control scheme is proposed to govern the transmission power of a CR node. For the second one, a cognitive media access control (MAC) employs carrier sense multiple access with collision avoidance (CSMA/CA) based contention control to coordinate the operation of CR nodes with transmission requests. These two control schemes are compared in terms of their resulting interference distributions. It is demonstrated that both power and contention controls are effective approaches to alleviate the interference caused by CR networks. Some indepth analysis for the impact of key parameters on the interference of CR networks is given via numerical studies as well. Index Terms – cognitive radio, interference modeling, power control, contention control. I.
Series expansion for interference in wireless networks
 IEEE Transactions on Information Theory
, 2012
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Interference and Outage in Mobile Random Networks: Expectation, Distribution, and Correlation
"... In mobile networks, distance variations caused by node mobility generate fluctuations in the channel gains. Such fluctuations can be treated as another type of fading besides multipath effects. In this paper, the interference statistics in mobile random networks are characterized by incorporating ..."
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Cited by 12 (2 self)
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In mobile networks, distance variations caused by node mobility generate fluctuations in the channel gains. Such fluctuations can be treated as another type of fading besides multipath effects. In this paper, the interference statistics in mobile random networks are characterized by incorporating the distance variations of mobile nodes to the channel gain fluctuations. The mean interference is calculated at the origin and at the border of a finite mobile network. The network performance is evaluated in terms of the outage probability. Compared to a static network, the interference in a single snapshot does not change under uniform mobility models. However, random waypoint mobility increases (decreases) the interference at the origin (at the border). Furthermore, due to the correlation of the node locations, the interference and outage are temporally and spatially correlated. We quantify the temporal correlation of the interference and outage in mobile Poisson networks in terms of the correlation coefficient and conditional outage probability, respectively. The results show that it is essential that routing, MAC, and retransmission schemes need to be smart (i.e,. correlationaware) to avoid bursts of transmission failures.
Aggregate Interference Modeling in Cognitive Radio Networks with Power and Contention Control
, 2010
"... Abstract—In this paper, we present interference models for cognitive radio (CR) networks employing various interference management mechanisms including power control, contention control or hybrid power/contention control schemes. For the first case, a power control scheme is proposed to govern the t ..."
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Cited by 10 (1 self)
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Abstract—In this paper, we present interference models for cognitive radio (CR) networks employing various interference management mechanisms including power control, contention control or hybrid power/contention control schemes. For the first case, a power control scheme is proposed to govern the transmission power of a CR node. For the second one, a contention control scheme at the media access control (MAC) layer, based on carrier sense multiple access with collision avoidance (CSMA/CA), is proposed to coordinate the operation of CR nodes with transmission requests. The probability density functions (PDFs) of the interference received at a primary receiver from a CR network are first derived numerically for these two cases. For the hybrid case, where power and contention controls are jointly adopted by a CR node to govern its transmission, the interference is analyzed and compared with that of the first
EnergyEfficient Repulsive Cell Activation for Heterogeneous Cellular Networks
"... Abstract—In this paper, we consider a twotier heterogeneous cellular network (HCN) where macrocells and distributed low power cells, namely daughtercells, are operated in a common spectrum. Due to the adhoc nature of daughtercell BS deployments such as pico and femto cells, the mutual interference ..."
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Cited by 5 (0 self)
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Abstract—In this paper, we consider a twotier heterogeneous cellular network (HCN) where macrocells and distributed low power cells, namely daughtercells, are operated in a common spectrum. Due to the adhoc nature of daughtercell BS deployments such as pico and femto cells, the mutual interference varies and obviously the coverage probability behaves differently in terms of transmit powers and densities of macrocells and daughtercells. In this paper, we employ repulsive cell activation in the interfering daughtercell network and see the impact of a minimum separation distance between the daughtercell BSs in terms of coverage under open access and power efficiency. The control of the minimum separation distance plays a role in balancing cell load effectively according to changing user density and is justified for the coexistence of low power daughtercells. The optimal minimum separation distance in terms of user density and target pertier user throughput requirements is found by a numerical search based on a simple bisection method. Numerical results show the benefit of cell repulsion in terms of increased user density support and less area power consumption. Index Terms—Heterogeneous cellular network, coverage probability, load balancing, power efficiency, repulsive cell activation, stochastic geometry. I.
New Insights into the Stochastic Geometry Analysis of Dense CSMA Networks
"... Abstract—Stochastic geometry proves to be a powerful tool for modeling dense wireless networks adopting random MAC protocols such as ALOHA and CSMA. The main strength of this methodology lies in its ability to account for the randomness in the nodes ’ location jointly with an accurate description at ..."
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Abstract—Stochastic geometry proves to be a powerful tool for modeling dense wireless networks adopting random MAC protocols such as ALOHA and CSMA. The main strength of this methodology lies in its ability to account for the randomness in the nodes ’ location jointly with an accurate description at the physical layer, based on the SINR, that allows to consider also random fading on each link. Existing models of CSMA networks adopting the stochastic geometry approach suffer from two important weaknesses: 1) they permit to evaluate only spatial averages of the main performance measures, thus hiding possibly huge discrepancies in the performance achieved by individual nodes; 2) they are analytically tractable only when nodes are distributed over the area according to simple spatial processes (e.g., the Poisson point process). In this paper we show how the stochastic geometry approach can be extended to overcome the above limitations, allowing to obtain node throughput distributions as well as to analyze a significant class of topologies in which nodes are not independently placed. I.
Large deviations of the interference in the ginibre network model. preprint (arxiv:1304.2234
, 2013
"... Under different assumptions on the distribution of the fading random variables, we derive large deviation estimates for the tail of the interference in a wireless network model whose nodes are placed, over a bounded region of the plane, according to the βGinibre process, 0 < β ≤ 1. The family o ..."
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Cited by 4 (1 self)
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Under different assumptions on the distribution of the fading random variables, we derive large deviation estimates for the tail of the interference in a wireless network model whose nodes are placed, over a bounded region of the plane, according to the βGinibre process, 0 < β ≤ 1. The family of βGinibre processes is formed by determinantal point processes, with different degree of repulsiveness. As β → 0, βGinibre processes converge in law to a homogeneous Poisson process. In this sense the Poisson network model may be considered as the limiting uncorrelated case of the βGinibre network model. Our results indicate the existence of two different regimes. When the fading random variables are bounded or Weibull superexponential, large values of the interference are typically originated by the sum of several equivalent interfering contributions due to nodes in the vicinity of the receiver. In this case, the tail of the interference has, on the logscale, the same asymptotic behavior for any value of 0 < β ≤ 1, but it differs from the asymptotic behavior of the tail of the interference in the Poisson network model (again on a logscale) [14]. When the fading random variables are exponential or subexponential, instead, large values of the interference are typically originated by a single dominating interferer node and, on the logscale, the asymptotic behavior of the tail of the interference is insensitive to the distribution of the nodes, as long as the number of nodes is guaranteed to be lighttailed. 1. Introduction. An
1The Spectral Efficiency of Slotted CSMA AdHoc Networks with Directional Antennas
"... The performance of wireless adhoc networks (WANET) is mainly limited by its selfinterference. This interference can be mitigated by applying smart access mechanisms and smart antennas. In this paper we analyze the performance of WANETs applying twophase slotted carrier sense multiple access (CSMA ..."
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Cited by 4 (3 self)
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The performance of wireless adhoc networks (WANET) is mainly limited by its selfinterference. This interference can be mitigated by applying smart access mechanisms and smart antennas. In this paper we analyze the performance of WANETs applying twophase slotted carrier sense multiple access (CSMA) mechanism and utilizing directional antennas. We present simple expressions that enable a high accuracy evaluation of the network area spectral efficiency (ASE). The results show that directional antennas only affect the ASE through a scaling factor, which depends on the antennas pattern and the channel path loss. The ASE expression also provides a simple and accurate evaluation of the optimal system parameters, including the optimal network density, interference threshold and users ’ rates. In particular, the ASE gain for a CSMA WANET over an ALOHA WANET is shown to be approximated very well by the exponent of the backoff probability. The accuracy of the results and the usefulness of the optimization procedure are also illustrated through numerical simulations. I.
On cognitive small cells in twotier heterogeneous networks
 in Proc. 9th Workshop on Spatial Stochastic Models for Wireless Networks (SpaSWiN 2013), Tsukuba Science City
"... AbstractIn a twotier heterogeneous network (HetNet) where small base stations (SBSs) coexist with macro base stations (MBSs), the SBSs may suffer significant performance degradation due to the interand intratier interferences. Introducing cognition into the SBSs through the spectrum sensing (e. ..."
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AbstractIn a twotier heterogeneous network (HetNet) where small base stations (SBSs) coexist with macro base stations (MBSs), the SBSs may suffer significant performance degradation due to the interand intratier interferences. Introducing cognition into the SBSs through the spectrum sensing (e.g., carrier sensing) capability helps them detecting the interference sources and avoiding them via opportunistic access to orthogonal channels. In this paper, we use stochastic geometry to model and analyze the performance of two cases of cognitive SBSs in a multichannel environment, namely, the semicognitive case and the fullcognitive case. In the semicognitive case, the SBSs are only aware of the interference from the MBSs, hence, only intertier interference is minimized. On the other hand, in the fullcognitive case, the SBSs access the spectrum via a contention resolution process, hence, both the intraand intertier interferences are minimized, but at the expense of reduced spectrum access opportunities. We quantify the performance gain in outage probability obtained by introducing cognition into the small cell tier for both the cases. We will focus on a special type of SBSs called the femto access points (FAPs) and also capture the effect of different admission control policies, namely, the openaccess and closedaccess policies. We show that a semicognitive SBS always outperforms a fullcognitive SBS and that there exists an optimal spectrum sensing threshold for the cognitive SBSs which can be obtained via the analytical framework presented in this paper.